I live in Lafayette but vacation there every year, my parents had a condo there for years. We just got back from Sand Destin. San Destin, Destin, Gratyon, Water Color Sea Side the whole 30A route is very nice, upscale for the most part there will be little to no spring breakers here as they can't afford it. There will be tons of them in Panama City. Panama City is practically not even comparable to Destin or the Sand Destin area. Remember there is Panama City Florida and Panama City Beach Florida which are right next to each other but different.
I don't think it is hot but I live in Lafayette, LA so I'm kinda used to heat and humidity. Florida is hot but nearly as humid as Louisiana and there is always are nearly always a nice breeze coming off the Gulf in and around Destin. The Destin area is going to be packed and riducles with vacationers from the middle of may through the middle of August it will spike again on Labor Day and around Easter. During the school months of Sept through May it is NICE, we used to go in October before our son was school age and beaches were empty, the water was crystal clear and the fishing was good. Now I'm from Louisiana so even when the fishing is good in Florida it doesn't even begin to hold a candle to the salt water fishing we have, not even close. Good days in an around Destin maybe 15 speckle trout total and you can only keep 5, good day here in Louisiana you catch your limit of specks 25 per man twice, going back and putting the first limit on ice while you go get another one and then leave them biting. Its stupid good, almost all year.
Prices have come down significantly in the Destin area over the previous 4 years, we looked at another condo for my parents at Sand Destin, not on the beach but on the golf course or bay side and could have picked something decent like 3 bed 2 bath 1,600 sq ft, deck, fire place, easily for 300K. Now the HOA was another 300+ per month but you don't do anything but put out your trash. Debbie blew into town while we were there and the morning after the wind stopped the entire development was full of uniformed mexican's with safety vest on picking up every single stick that blew down. By lunch time you could not tell a tropical depression had just blown through.
The whole Destin area or 30A vibe is nice and the locals are friendly but summer is going to be slam packed with vacationers 24/7 which means lots of traffic, lots. Moreover Destin and the 30A is without question going upscale and around the resorts things are pricey. We went out to eat every night 8 of us and our bill was never less than 253 and was as high one night as 645. I'm sure the locals have other places to eat but everything in that area seems to be going upscale or high end. So your cost of living at least during peak season is going to be high I would imagine.
Just go down there and check it out, you will see what I mean though about Panama City there simply is not comparison when your talking about the Destin area to Panama City. Something else you may want to check out is the area down around Port St. Joe and Cape San Blas and Mexico Beach different places for sure but all have really good feels to them. Port St. Joe especially, now that said Port St. Joe and the other towns are small off the beaten path and all about an hour east of Panama City and would be considered rural beach communities but there interesting laid back places for sure.
Hope this helps.